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Williams, T. H. L.

Publications and source records attributed to Williams, T. H. L..

Evaluation of space SAR as a land-cover classification

The multidimensional approach to the mapping of land cover, crops, and forests is reported. Dimensionality is achieved by using data from sensors such as LANDSAT to augment Seasat and Shuttle Image Radar (SIR) data, using different image features such as tone and texture, and acquiring multidate data. Seasat, Shuttle Imaging Radar (SIR-A), and LANDSAT data are used both individually and in combination to map land cover in Oklahoma. The results indicates that radar is the best single sensor (72% accuracy) and produces the best sensor combination (97.5% accuracy) for discriminating among five land cover categories. Multidate Seasat data and a single data of LANDSAT coverage are then used in a crop classification study of western Kansas. The highest accuracy for a single channel is achieved using a Seasat scene, which produces a classification accuracy of 67%. Classification accuracy increases to approximately 75% when either a multidate Seasat combination or LANDSAT data in a multisensor combination is used. The tonal and textural elements of SIR-A data are then used both alone and in combination to classify forests into five categories.

Brisco, B.

Mapping irrigated lands in Western Kansas from Landsat

A description is presented of a multidate visual interpretation technique for identifying and mapping irrigated lands in Western Kansas based on gray tone interpretation of Landsat imagery. The technique provides detailed maps of irrigated lands that can be updated yearly (from 1972 onwards) and used as the basis for calculations of water use and its temporal trends. A review of remote sensing work on irrigated lands indicates that three different types of study have evolved, involving various combinations of desired final data and the means of arriving at it. Attention is given to crop characteristics, the development of an interpretation technique, the interpretation procedure, the computer assisted output, and aspects of verification and accuracy. It is pointed out that the considered technique is likely to be applicable to similar situations of a semi-arid area dominated by a small number of crops.

Williams, T. H. L.

Low-cost digital image processing on a university mainframe computer

The advantages and limitations of using university mainframe computers in digital image processing instruction are listed. Aspects to be considered when designing software for this purpose include not only two general audience, but also the capabilities of the system regarding the size of the image/subimage, preprocessing and enhancement functions, geometric correction and registration techniques; classification strategy, classification algorithm, multitemporal analysis, and ancilliary data and geographic information systems. The user/software/hardware interaction as well as acquisition and operating costs must also be considered.

Williams, T. H. L.

Instructional image processing on a university mainframe: The Kansas system

An interactive digital image processing program package was developed that runs on the University of Kansas central computer, a Honeywell Level 66 multi-processor system. The module form of the package allows easy and rapid upgrades and extensions of the system and is used in remote sensing courses in the Department of Geography, in regional five-day short courses for academics and professionals, and also in remote sensing projects and research. The package comprises three self-contained modules of processing functions: Subimage extraction and rectification; image enhancement, preprocessing and data reduction; and classification. Its use in a typical course setting is described. Availability and costs are considered.

Williams, T. H. L.